Ever since I visited Italy over a decade ago my inner geek has had a fascination with traffic engineering. If you’ve visited Italy, or many similar places, you probably know why. Traffic appears chaotic, thanks in part to what appears at first glance to be a lack of signals and other controls. To those of us with highly-regimented traffic control systems this feels crazy and even scary. Until we realize something:

Traffic flows continuously, pretty much everywhere.

Now it may not be a fast, but the net effect is often more flow than the stop-and-go signal-driven batch movement that exists in many U.S. cities. Traffic engineers have recognized this as well, with many cities intentionally removing signals.

In fact, the chaos associated with traffic in developing countries is becoming all the rage among a new wave of traffic engineers in mainland Europe and, more recently, in the United Kingdom. It’s called “second generation” traffic calming, a combination of traffic engineering and urban design that also draws heavily on the fields of behavioral psychology and — of all subjects — evolutionary biology. Rejecting the idea of separating people from vehicular traffic, it’s a concept that privileges multiplicity over homogeneity, disorder over order, and intrigue over certainty. In practice, it’s about dismantling barriers: between the road and the sidewalk, between cars, pedestrians and cyclists and, most controversially, between moving vehicles and children at play.

The psychology of this is particularly interesting. In countries with highly-controlled traffic the emphasis has been on reducing chaos by removing human decisions. This has had the negative effect of disengaging drivers (and pedestrians, bikers, etc.) from the environment, which can actually create more risk.

“One of the characteristics of a shared environment is that it appears chaotic, it appears very complex, and it demands a strong level of having your wits about you,” says U.K. traffic and urban design consultant Ben Hamilton-Baillie, speaking from his home in Bristol. “The history of traffic engineering is the effort to rationalize what appeared to be chaos,” he says. “Today, we have a better understanding that chaos can be productive.”

Hamilton-Baillie argues that the key to improving both safety and vehicular capacity is to remove traffic lights and other controls, such as stop signs and the white and yellow lines dividing streets into lanes. Without any clear right-of-way, he says, motorists are forced to slow down to safer speeds, make eye contact with pedestrians, cyclists and other drivers, and decide among themselves when it is safe to proceed.

Removing traditional signals can be scary or disturbing. A first step is often replacing intersections with traffic circles, or roundabouts. Those of us that have lived in the northeast U.S. know they are fairly common, but here on the west coast they’re still rare.

A few years ago my small town of 10,000 replaced a complex five-way intersection with a traffic circle. Believe it or not, that circle reduced the number of stop lights in our town by 33% – from 3 to 2! Even though the number of traffic accidents dropped to about zero and flow is far smoother, the community remains very divided. I personally love it, and zip through the circle at least a couple times a day.

Now the city wants to replace one of the two remaining lights with another traffic circle. Once again it makes a lot of sense as the intersection being considered is complex – three streets plus the on and off ramps for the Pacific Coast Highway. One issue is that it is a half block from the high school, and some residents are concerned about kids walking and driving near a “dangerous circle.”

We have part of the community that has looked at the science described above, as well as the improved results from our first traffic circle, and are proponents of the new circle. And we have another part that is analyzing the proposal on a more emotional level, often based on a handful of anecdotal close calls with the existing traffic circle, and legitimate and understandable concern about our school kids. I don’t know what the city will decide.

It strikes me that this is very similar to what many of us have gone through with lean transformations. Traditional batch manufacturing makes sense, and one piece flow feels counterintuitive. Even after seeing it in action, perhaps even something as “real” as the envelope-stuffing exercise, dishwasher kaizen, or lean bathroom, it sometimes just doesn’t seem right.